The castle of Wawel is a strong complex that has been erected for centuries on the limestone outcrop on the left bank of the Vistura River in Krakow, Poland. The complex consists of many buildings and fortifications. The largest and most famous of these are the Royal Castle and Wawel Cathedral. Some of Wawel's oldest stone buildings, such as the Roundhouse of the Virgin Mary, can be traced back to 970AD. Wawel was of great significance to the Polish people: first became a political power center after a thousand years and a major fortress of the Visdura tribe in the 9th century. The first historical ruler of the Piast dynasty, Misko I of Poland (c.965– 992), and his successors: the brave Bolesaw I and Misko II (1025 – 1034) chose Wawel as their residence. Meanwhile, Wawel became one of Poland's major Christian centers, where early Romanesque buildings were first built, including a stone cathedral, serving the bishops of Krakow in 1000. From the reign of Kassimir (1034-1058), Wawel became the main political and administrative center of Poland. Wawel Cathedral was not only the place where the Polish kings were crowned, but also their mausoleum. It later became the national pantheon.